DNA: Structure and Function http://www.dbsm.uninsubria.it/genetic/HumanGenetic/images/dnanim.gif Chapter 12 Section 1

The Molecule of Heredity The Blueprint of Life DNA Deoxyribose Nucleic Acid The Architect of Life The First three-dimensional xerox machine The Molecule of Heredity The Blueprint of Life Life Instruction Manual

DNA

Why Study DNA? To truly understand genetics, biologists first had to discover the chemical structure of the gene This would then help them understand how genes control the inherited characteristics of living things Gene expression is what enables cells of the same organism to take on so many different sizes, shapes and functions (even though just about every cell in an individual contains the same DNA) http://www.worldofteaching.com/powerpoints/biology/The%20Human%20Genome%20Project.ppt

Review What organelle is known as the control center of the cell? What structures are found in the nucleus? What are short segments of chromosomes? 4. What are genes/chromosomes composed of? 5. How do genes/chromosomes control the activity of the cell? nucleus chromosomes genes http://www.nlm.nih.gov/medlineplus/ency/images/ency/fullsize/8770.jpg http://files.turbosquid.com/Preview/Content_on_2_26_2005_13_38_09/DNA8-400.jpg71abe163-6969-448a-8c20-b7209efeefb0Large.jpg http://images.google.com/imgres?imgurl=http://micro.magnet.fsu.edu/cells/nucleus/images/nucleusfigure1.jpg&imgrefurl=http://micro.magnet.fsu.edu/cells/nucleus/nucleus.html&h=266&w=359&sz=35&hl=en&start=5&um=1&tbnid=PqWl9XHUB0jszM:&tbnh=90&tbnw=121&prev=/images%3Fq%3Dnucleus%26svnum%3D10%26um%3D1%26hl%3Den%26rls%3DGGLB,GGLB:1969-53,GGLB:en%26sa%3DN DNA produce proteins that regulate cell functions and become cell structures

Review Review http://www.nlm.nih.gov/medlineplus/ency/images/ency/fullsize/8770.jpg http://files.turbosquid.com/Preview/Content_on_2_26_2005_13_38_09/DNA8-400.jpg71abe163-6969-448a-8c20-b7209efeefb0Large.jpg http://images.google.com/imgres?imgurl=http://micro.magnet.fsu.edu/cells/nucleus/images/nucleusfigure1.jpg&imgrefurl=http://micro.magnet.fsu.edu/cells/nucleus/nucleus.html&h=266&w=359&sz=35&hl=en&start=5&um=1&tbnid=PqWl9XHUB0jszM:&tbnh=90&tbnw=121&prev=/images%3Fq%3Dnucleus%26svnum%3D10%26um%3D1%26hl%3Den%26rls%3DGGLB,GGLB:1969-53,GGLB:en%26sa%3DN

History 1869 - Friedrich Miescher – “discovered” DNA in nucleus Frederick Griffith History Rosalind Franklin X-ray of double helix James Watson Francis Crick Martha Chase Alfred Hershey 1869 - Friedrich Miescher – “discovered” DNA in nucleus 1928 - Frederick Griffith – Identified DNA as source of genetic material using bacteria 1930’s - Oswald Avery, Colin MacLeod and Maclyn McCarty - Confirmed that genes made of DNA 1950 - Alfred Hershey and Martha Chase confirmed DNA is the biochemical of heredity using radioactive markers bacteriophages 1952- Maurice Wilkins and Rosalind Franklin X-rayed DNA to show repeating nucleotide structure 1953- James Watson and Francis Crick combined data to create a 3-D model of structure called the double helix Oswald Avery Maclyn McCarty

Watson-Crick Model http://upload.wikimedia.org/wikipedia/commons/8/81/ADN_animation.gif

DNA Structure Is a polymer of 1000’s of nucleotide monomers Is a double strand of covalently bonded nucleotides in twisted ladder shape twisted ladder shape = double helix http://www.msu.edu/~sigmaxi/images/DNA_Anim_Blue255_bg.gif

DNA Shape Double helix: 2 spirals wound around each other But joined in the middle

DNA Structure Is a polymer of 1000’s of nucleotide monomers Is a double strand of covalently bonded nucleotides in twisted ladder shape twisted ladder shape = double helix ‘Rungs’ of ladder = nitrogen bases ‘Sides’ of ladder = sugar & phosphate groups (also called the DNA backbone) Sugar Phosphate Backbone http://www.msu.edu/~sigmaxi/images/DNA_Anim_Blue255_bg.gif

Nucleotide Nucleotide- Individual unit of DNA. Made of three parts: Deoxyribose (5-carbon sugar) Phosphate group A nitrogen-containing base

Bases Four nitrogen-containing bases Adenine Guanine Cytosine Thymine

Bases Adenine double ringed = Guanine purines Thymine single ringed = Cytosine purines pyrimidines

Nucleotide Deoxyribose (like ribose) is a sugar with 5 carbon  atoms in a ring Oxygen is one of the ring members In Deoxyribose, one of the OH groups is missing and replaced with hydrogen Thus deoxy = - 1 oxygen P base sugar H OH

Nucleotide P - the Phosphate group Is important because it links the sugar on one nucleotide with the phosphate of the next nucleotide to make a polynucleotide Nucleotides are connected to each other via a covalent bond P base sugar

‘Base Pairing Rule’ Bases are paired together in specific manner Because of chemical structure and shape Adenine only pairs with Thymine Guanine only pairs with Cytosine Exactly enough room for only one purine and one pyramide base between the two strands of DNA

‘Base Pairing Rule’ Bases held together in ‘rungs’ by weak hydrogen bonds 2 hydrogen bonds between A & T 3 hydrogen bonds between C & G

DNA

DNA Function Scientists wondered how DNA worked. They knew genes do these critical things: Carry information from one generation to another Put information to work to determine an organism’s characteristics Can be easily copied Store and transmit genetic information needed for all cell functions In order to do these things it had to be a special molecule!

Understanding DNA Our knowledge of DNA put to use: Inheritance/ Genetic Counseling Cell function/protein synthesis Embryonic development/gene regulation Evolution/ phylogenetic relationships Medicine/genetic diseases Genetic engineering/ recombinant DNA

Structure of DNA Review Nucleotide Hydrogen bonds Sugar-phosphate backbone Key Adenine (A) Thymine (T) Cytosine (C) Guanine (G)

Structure of DNA Review Pyrimidines Purines Adenine Guanine Cytosine Thymine Bases Phosphate group Deoxyribose

DNA’s Size To get an idea of the size of the human genome present in each of our cells, consider the following analogy: If the DNA sequence of the human genome were compiled in books, the equivalent of 200 volumes the size of a Manhattan telephone book (at 1,000 pages each) would be needed to hold it all. It would take about 9.5 years to read out loud (without stopping) the 3 billion bases in one person's genome sequence, calculated on a reading rate of 10 bases per second, equaling 600 bases/minute, 36,000 bases/hour, 864,000 bases/day, 315,360,000 bases/year. http://www.riverdeep.net/current/2000/07/072100_genome_arc.jhtml http://genomics.energy.gov/ Human Genome Project

DNA How Am I Packaged? Nitrogen bases 1. Are like letters in the code 2. Put them in different order make a different gene http://www.nlm.nih.gov/medlineplus/ency/images/ency/fullsize/8770.jpg http://files.turbosquid.com/Preview/Content_on_2_26_2005_13_38_09/DNA8-400.jpg71abe163-6969-448a-8c20-b7209efeefb0Large.jpg http://images.google.com/imgres?imgurl=http://micro.magnet.fsu.edu/cells/nucleus/images/nucleusfigure1.jpg&imgrefurl=http://micro.magnet.fsu.edu/cells/nucleus/nucleus.html&h=266&w=359&sz=35&hl=en&start=5&um=1&tbnid=PqWl9XHUB0jszM:&tbnh=90&tbnw=121&prev=/images%3Fq%3Dnucleus%26svnum%3D10%26um%3D1%26hl%3Den%26rls%3DGGLB,GGLB:1969-53,GGLB:en%26sa%3DN

DNA Package Genes 1. Are like words made up of letters HAT A DNA CAT DOG Package C A Genes 1. Are like words made up of letters 2. A group of nitrogen bases that makes sense 3. Tells the cell to do something T http://www.nlm.nih.gov/medlineplus/ency/images/ency/fullsize/8770.jpg http://files.turbosquid.com/Preview/Content_on_2_26_2005_13_38_09/DNA8-400.jpg71abe163-6969-448a-8c20-b7209efeefb0Large.jpg http://images.google.com/imgres?imgurl=http://micro.magnet.fsu.edu/cells/nucleus/images/nucleusfigure1.jpg&imgrefurl=http://micro.magnet.fsu.edu/cells/nucleus/nucleus.html&h=266&w=359&sz=35&hl=en&start=5&um=1&tbnid=PqWl9XHUB0jszM:&tbnh=90&tbnw=121&prev=/images%3Fq%3Dnucleus%26svnum%3D10%26um%3D1%26hl%3Den%26rls%3DGGLB,GGLB:1969-53,GGLB:en%26sa%3DN

DNA The cat sat. One dog ate. The big hat. Package DNA strand 1. Are like sentences made up of words 2. A long line of genes on each DNA strand http://www.nlm.nih.gov/medlineplus/ency/images/ency/fullsize/8770.jpg http://files.turbosquid.com/Preview/Content_on_2_26_2005_13_38_09/DNA8-400.jpg71abe163-6969-448a-8c20-b7209efeefb0Large.jpg http://images.google.com/imgres?imgurl=http://micro.magnet.fsu.edu/cells/nucleus/images/nucleusfigure1.jpg&imgrefurl=http://micro.magnet.fsu.edu/cells/nucleus/nucleus.html&h=266&w=359&sz=35&hl=en&start=5&um=1&tbnid=PqWl9XHUB0jszM:&tbnh=90&tbnw=121&prev=/images%3Fq%3Dnucleus%26svnum%3D10%26um%3D1%26hl%3Den%26rls%3DGGLB,GGLB:1969-53,GGLB:en%26sa%3DN

DNA Package Chromosomes 1. Are like books full of sentences 2. DNA strand twists around and around itself http://www.nlm.nih.gov/medlineplus/ency/images/ency/fullsize/8770.jpg http://files.turbosquid.com/Preview/Content_on_2_26_2005_13_38_09/DNA8-400.jpg71abe163-6969-448a-8c20-b7209efeefb0Large.jpg http://images.google.com/imgres?imgurl=http://micro.magnet.fsu.edu/cells/nucleus/images/nucleusfigure1.jpg&imgrefurl=http://micro.magnet.fsu.edu/cells/nucleus/nucleus.html&h=266&w=359&sz=35&hl=en&start=5&um=1&tbnid=PqWl9XHUB0jszM:&tbnh=90&tbnw=121&prev=/images%3Fq%3Dnucleus%26svnum%3D10%26um%3D1%26hl%3Den%26rls%3DGGLB,GGLB:1969-53,GGLB:en%26sa%3DN

DNA Package Nucleus 1. Is like a bookcase 2. Inside the cell, where all the chromosomes are stored http://www.nlm.nih.gov/medlineplus/ency/images/ency/fullsize/8770.jpg http://files.turbosquid.com/Preview/Content_on_2_26_2005_13_38_09/DNA8-400.jpg71abe163-6969-448a-8c20-b7209efeefb0Large.jpg http://images.google.com/imgres?imgurl=http://micro.magnet.fsu.edu/cells/nucleus/images/nucleusfigure1.jpg&imgrefurl=http://micro.magnet.fsu.edu/cells/nucleus/nucleus.html&h=266&w=359&sz=35&hl=en&start=5&um=1&tbnid=PqWl9XHUB0jszM:&tbnh=90&tbnw=121&prev=/images%3Fq%3Dnucleus%26svnum%3D10%26um%3D1%26hl%3Den%26rls%3DGGLB,GGLB:1969-53,GGLB:en%26sa%3DN

DNA Package So what would a library full of rows and rows of bookcases represent? many cells together which is a tissue http://www.nlm.nih.gov/medlineplus/ency/images/ency/fullsize/8770.jpg http://files.turbosquid.com/Preview/Content_on_2_26_2005_13_38_09/DNA8-400.jpg71abe163-6969-448a-8c20-b7209efeefb0Large.jpg http://images.google.com/imgres?imgurl=http://micro.magnet.fsu.edu/cells/nucleus/images/nucleusfigure1.jpg&imgrefurl=http://micro.magnet.fsu.edu/cells/nucleus/nucleus.html&h=266&w=359&sz=35&hl=en&start=5&um=1&tbnid=PqWl9XHUB0jszM:&tbnh=90&tbnw=121&prev=/images%3Fq%3Dnucleus%26svnum%3D10%26um%3D1%26hl%3Den%26rls%3DGGLB,GGLB:1969-53,GGLB:en%26sa%3DN